This project focuses on improving public health practice through translation research in the context of a population trial aimed at the prevalence reduction of child maltreatment. This trial, called the U.S. Triple P System Population Trial, is the only known study on prevention of child maltreatment that has randomly assigned geographical areas (in this case 18 counties) to condition and is examining impact on population indicators of child maltreatment. The public-health-based intervention is the Triple P (Positive Parenting Program) system for which efficacy and effectiveness has been well established through over 30 previous RCTs. The key aims are: (1) to identify and better understand facilitators and impediments to maintenance of service-provider implementation of evidence-based parenting interventions for prevention of child maltreatment;(2) to evaluate how well the translation of the evidence-based parenting interventions into a broad-scale dissemination strategy has succeeded with respect to the sustaining the prevention of child maltreatment over multiple years with respect to child out-of-home placements, child hospitalizations and emergency-room visits for maltreatment-related injuries, and child maltreatment cases;(3) to evaluate the cost effectiveness of the population-wide dissemination over multiple years;and (4) to characterize variation in child-maltreatment prevention outcomes across counties and explore associations with implementation and socio-demographic variables. The methodology includes randomization and experimental control at the level of county (controlling for prior rates of child abuse), repeated field assessments with 400 service providers, and ecological dissemination of the public health intervention.